1. Field of the Invention
This invention relates to root prevention technology for preventing extrusion of plant roots into the outside part of the soil layer and particularly relates to insufficient prevention of other waterproof functions for buildings and to building damage prevention.
2. Description of the Related Art
In recent years there have been active attempts to cultivate plants on a large scale on building rooftops or other spaces, to plant trees in inorganic spaces in urban areas, to make views more beautiful and to suppress the heat island phenomenon. However, because the expansion capability of plant roots is so powerful, they have extruded into the inner waterproof layers of concrete foundations and asphalt.
As a result, cracks have been caused in buildings, roads and underground pipelines which have lead to a number of problems. For example, when growing trees on rooftops, it is easy for the plant roots to get into the waterproof layer made of asphalt and to cause leakage problems. Also, when cultivating trees for lining the shoulders of outdoor roads, the roots of these trees get in sewage pipes from the joints and cause blockage problems.
Consequently, root prevention countermeasures have been applied for quite some time. For example, there have been instances where such materials as woven cloth or nonwoven fabric with chemical root-preventing treatment applied have been laid underneath root cultivation layers. However, there are also cases where the root-preventing treatment agents cause damage to the growth of the plant roots, debilitating effects cannot be avoided over the years and initial costs are high.
Furthermore, attempts to build plastic sheets as root-preventing countermeasures have also been made. However, without making an analysis of the root-preventing functions of plastic sheets, in certain cases it has frequently happened that the sheets have been too thick and this has caused problems in application or conversely when they have been too thin, no root prevention results have been obtained. Additionally, there has been the problem of plant roots extruding from the overlapping parts of the sheets. In order to prevent this from occurring from the overlapping parts, attempts have also been made to provide root prevention treatment to the overlapping parts but manufacturing costs have increased and application has been very troublesome and inconvenient.
Furthermore, the following are references pertaining to this invention    [Patent document No. 1] Japanese Published Unexamined Application Publication No. 2007-49957    [Patent document No. 2] Japanese Published Unexamined Application Publication No. 2007-20464    [Patent document No. 3] Japanese Published Unexamined Application Publication No. 2007-6798    [Patent document No. 4] Japanese Published Unexamined Application Publication No. 2006-230355    [Patent document No. 5] Japanese Published Unexamined Application Publication No. 2006-204190    [Patent document No. 6] Japanese Published Unexamined Application Publication No. 2006-180746    [Patent document No. 7] Japanese Published Unexamined Application Publication No.    [Patent document No. 8] Japanese Published Unexamined Application Publication No. 2005-58178    [Patent document No. 9] Japanese Published Unexamined Application Publication No. 2002-335762    [Patent document No. 10] Japanese Published Unexamined Application Publication No. 2001-178269    [Patent document No. 11] Japanese Published Unexamined Application Publication No. 11-32578
The objective of this invention is to solve the above-mentioned conventional problems by achieving root prevention technology to present definite root-preventing effectiveness at low initial cost with easy, stable application and with outstanding durability.